Zuckerberg, who appeared at ease while trading laughs with his interviewer, for the first time elaborated on technical struggles that have impeded Facebook from creating a user- and advertiser-friendly mobile application. The company spent too long trying to build mobile products using a programming language known as HTML5, Zuckerberg said.

‘Biggest Mistake’

“The biggest mistake we’ve made as a company is betting too much on HTML5,” he said.